Then create the database or simply display the SQL using manage.py sqlall myapp and save it. Then comment the last class - BugTest. Recreate the database or show the SQL again and save it. If you diff it, there are two differencies:

There's no table bugtest in the second SQL dump because there was no definition for it. Which is correct.

The second difference is probably a bug - there's no constraint for ServiceVariant class refering to Service. The ALTER TABLE myapp_servicevariant ADD CONSTRAINT ... is missing.